Preforming die



May 29, 1945.

M. M. BURGESS PRE ORMING DIE Filed June 23, 1942 3 Shets-Sheet 1 1:32- II J \QS /I INVENTOR 4 El 38 BY M-aqzzus Mfilllfgr (C 4/ M 1% 7/2, 0 i IATTORNESS.

M. M. BURGESS PREFORMING DIE May 29, 194-5.

Filed Juhe 23 1942 3 Sheets-Sheet 2 ATTORNEYli W 4 1 pl y 29,19 5. 7mMsuReEss' 2,3 1,128

PREFORMING DIE Filed June 23, 1942 3 Sheets-Sheet 3 INVENTOR ATTQRNE Y3Patented May 29, 1945 PREFORMIN G DIE Magnus M. Burgess, Detroit, Michassignor to Sheller Manufacturing Corporation, Portland, Ind., acorporation of Indiana Application June 23, 1942, Serial No. 448,079

Claims. The present invention relates to the molding of so-calledplastic materials about a supporting or reinforcing core. Such materialsinclude; among others, thermoplastics, such as Tenite, thermosettingmaterials, such as Bakelite, and cold molded materials, such asasphaltic compositions. The invention is particularly advantageous whenapplied to the preforming of such plastic materials around. the corewhen the materials are supplied initially in a powdered or granular (i.e. particulated) form, but the invention may also be applied to plasticssuch as rubber which are supplied initially in the form of roughlyshaped slabs or pieces.

It has been found desirable to preform such materials under pressureabout the core-piece prior to the final molding operation in order toreduce waste by reducing or eliminating the flash which is formed duringthe final molding operation and also to evenly distribute the materialabout the core-piece prior to the final molding operation. If theplastic is particulated in form, sufficient pressure is employed to holdthe particles of plastic material together until the article can beplaced in the final molding press; in the case of uncured rubber, thepressure imparts a temporary form to the mass.

Hitherto it has been the practice, particularly in the molding ofannular members, such as vehicle steering wheels, from particulatedmaterial to preform the plastic material in two separate pieces, each ofwhich is adapted to envelop half of the core of the steering wheel rim.When this practice is followed, the core-piece and the two sections ofpro-molded material are assembled in proper position in themolding-press for the final molding operation. While this practiceeliminates waste and results in an even distribution of the material, itis found that the mating surfaces of the two pre-molded sections ofplastic material do not bond properly due to the formation of a glazed,partially set condition on the surfaces of paratus and method which areespecially advantageous when-applied to a particulated plastic material.

A more specific object of the invention is to provide such an apparatusadapted to preform plastic material entirely around an annular coremember, such as the rim of a steering wheel.

Another object of the invention is to provide an" apparatus adapted topreform plastic material entirely around not only the annular rim coreof a vehicle wheel, but also the spokes and hub of the wheel in a singleoperation.

A still further object is to provide an apparatus of the type mentionedwhich is elfective even though the particulated plastic materialemployed is reduced many times in volume during,

the preforming operation.

Other objects, which include the provision of an apparatus of the typementioned which is rapid and fool-proof in its operationfwill becomeapparent from the following specification, the accompanying drawings,and the appended claims.

In the drawings, in which like numerals are used to designate like partsin the several views throughout:

Figure 1 is a vertical section through a suitable die mechanism for usein carrylng'out the invention, showing the die members in their fullyopen position. The section is taken on the irregular line l-i of Figure2; 1

Figure 2 is a plan view of the lower half of the die mechanism;

Figure 3 is a sectional view corresponding to Figure 1, showing the diemembers in a partially closed position;

Figure 4 is a similar vertical section, showing the die members in theirfully closed position;

Figure 5 is a plan view similar to Figure 2 of the lower half of amodified form of die'mechanism; I

Figure 6 is a sectional view taken on line 6 fi of Figure 5, showing themodified form of die It) and H adapted to be secured to the relativelymoving members of any suitable form of press. Secured, respectively, tothe supporting members Ill-and H are a pair of annular plungers l2 andI3 which are secured in annular slots in the members in any suitablemanner, such as by cap screws l4 and l5, for projection toward eachother.

A die member l6 has a lost motion connection with the lower supportingmember ll through three cap screws l8, which are threaded into suitabletapped openings in the supporting member ll and locked into position bymeans of lock nuts l9. Cap screws l8 extend through suitable bores 20 inthe die member I6, and the heads of the cap screws are adapted to slidein counterbores 25 in the upper ends of the bores 2c. The die member itis constantly urged away from the supporting member by three springs 22equally spaced about the periphery of the die member it and seated inthe bores 23 and 24 in the die member and supporting member,respectively.

The outer surface 25 of the die member as is cylindrical in contour andis adapted to have a sliding fit within the annular plunger 63.

The central portion of the die member 06 is provided with a, centralrecess 21! and a central spindle 30 projecting upwardly from the bottomof the recess and adapted to receive the hub 2 of the steering wheel inthe manner shown in dotted lines in Figure 1. When the steering wheel ispositioned on the stud til, its spokes 3 project outwardly throughradial grooves 32 formed in the upper surface of the die member to. Theouter ends of the grooves 32 are reduced, as shown at 33, in order toclosely fit the spokes and thus prevent flow of the plastic materialthrough the grooves during the preforming operation.

. A second die member 35 is also connected to the lower supportingmember M by a lost motion connection comprising four cap screws to,which are threaded into suitable tapped openings in the supportingmember M and locked into position by means of lock nuts 39. The shanksof the cap screws 38 have a sliding fit in bores fill inthe die member36, which bores are countersunk at all at their upper ends to receivethe heads of the cap screws. The die member 35 is normally urged awayfrom the supporting member if] by four springs M having their endsseated in suitable bores 65 and A6 in the die member and supportingmember, respectively. The inner surface 8 of the die members so is'cylindrical in contour and is adapted to have a sliding fit with theexterior surface of the annular plunger 83.

The upper supporting member it carries an in her die member 50, which issimilar in construction to the inner die member it except that it lacksthe wheel supporting means. Die member 5b is likewise provided with 'alost motion connection with the supporting member llEl, suchcohnectioncomprising cap screws 52 threaded into suitable tapped openings in thesupporting member it and locked into position by'lock nuts 53. The capscrews .52 have a sliding fit in bores 56 in the die member 5t, and thebores 5d are provided with countersunk lower ends 55 to receive theheads of the cap screws 52. Three equally spaced springs 56, similar inconstruc-.

tion and arrangement to the springs 22, normally urge the die 50downwardly with respect to the supporting member If). The outer surface58 or the die member 50 is cylindrical in form and is adapted to have asliding fit within the annular plunger E2. The lower portion of the die50 is provided with three radially distributed grooves 59 adapted toreceive and fit the upp r P rtions of the spokes 4 when thedie membersare closed.

The supporting member it also carries an sliding fit in boresBB in thedie member Gil, which bores at their lower ends are countersunk at (itto receive the heads of the cap screws ill. The inner surface 155 of thedie member {it is cylindrical in form, and is adapted to have a slidingfit on the outer surface of the annular plunger l2. Four springs 65,constructed and arranged in the manner of springs id, are locatedbetween the supporting member it and the die member 6t and serve'to urgethe die member til into spaced relation to the supporting member lb.

It will be apparent that with the construction so far described when thesupporting members it and it are fully separated, as shown in Figure l,the heads of the cap screws 88, 38, 52 and [it engage the bottoms of thecountersunk openings in which they fit and cause a separation of the diemembers as. and ill, on one hand, and 3b and G0, on the other, in spiteof the action of springs 22, dd, 5% and 86, tending to force the diemembers toward each other. The parts are so arranged that upon such fullseparation, suiilcle'nt space will be providedbetween the die members topermit insertion of the wheel or other core member in the manner shownin solid lines in Figure l. The final position of the wheel or coremember is illustrated in dotted lines in Figure l.

After the core of the steering wheel frame is placed in the positionillustrated in dotted lines in Figure l, the press is operated to causethe supporting members it and ill to move toward each other until thelower inner die it contacts the upper inner die 5t and the lower outerdie 56 similarly contacts the'upper outer die 69, which position of theparts is illustrated in Figure 3. It will be observed that during thismovement the springs 22, dd, 56 and to hold the various die members intheir fully spaced relation to their supporting members, with the resultthat there is little or no relative movement between the plungers l2 andit and the die member's in contact with them. Such closing of the diemem bers forms a closed annular chamber, indicated generally at 68, theinner sidewall of which is formed by the cylindrical surfaces 25 and ofthe die members it and 50, respectively, and the outer side Walls ofwhich are formed by the cylindrical walls All? and 65 of the die members36 and 58, respectively. 'Ihe bottom wall of the annular chamber isformed by the end of the annular plunger 03, we the top wall is formedby the end of the annular plunger [12. Since the spokes 3 have a closefit with the grooves and 59 in die members it and 05, respectively, theannular chamber is entirely closed and the core or rim ll is positionedcentrally oi the chamber.

measured quantity of. material sufiicient to completely fill the closedannular chamber 68 is injected into the chamber, the operator knows thatthe entire chamber is filled and that the material is equallydistributed around the annular core or outer die, member 66, similar tothe die member rim Thereupon the press is operated to turther move. thesupporting members iii and it toward each other to the fully closedposition illustrated in Figure 4. It will be observed that during thisfinal closing movement the springs 22, M, 56 and 88 are compressed andthe die members positively abut against the supporting members I and.II. Since this final closing movement in the particular constructionillustrated is greater than the length of the counterbores ZI,

4|, 55 and 84, the studs I8 are offset circum ferentially with respectto the studs 52, and the studs 38 are likewise offset from the studs GIand pockets are provided for the reception of the heads of these studsin the final closing movement. As best shown in Figures S and 4, the

heads of studs 38 project into pockets 14 in thedie member 80 when theparts are in their fully closed position. The heads of the remainingstuds project into similar pockets.

It should be noted that during the first part of r the parts, and inparticular the stroke of the' plungers, may be reduced or increased toaccommodate materials having less or greater degrees of compression.

During the final preforming movement, the weight of they die members I6,36, 50 and 80 is supported by the springs 22 and 44. Preferably, thesprings 22 and 44 are made substantially stiifer than the springs 58 and68, so that the former will overcome the compressive force exerted bythe latter and hold the die members substantially midway between thesupporting members In and during the final preforming movement, since bythat means theplungers I2 and I3 will be caused to move simultaneouslyand at the same rate toward the annular core 4. Sufllcient pressure isapplied to temporarily bond the particles of material together, the bondbeing merely sufficient to permit handling of the bonded core betweenthepreforming press and the final molding press.

The modified form of the invention shown in Figures 5 and 6 is similarin principle of operation to that illustrated in. Figures 1 to 4,inclusive, but it is-adapted not only to mold plastic materials aroundthe rim of a steering wheel frame but also, at the same time, about thespokes and hub portion, in consequence of which the die members aredifferently shaped from those previously described and additionalplungers are provided.

. As shown in Figures 5 and 6; the frame or core of the steering wheelincludes a hub 'sleeve80, four radially extending spokes 8|, a rim 82,and

an inner reinforcing ring 88 connecting the spokes Y adjacent the hub;and the die mechanism is adapted to preform plastic material entirelyabout all portions of the frame or core except the top and bottomextremities of the hub sleeve 80. As in the previous form of theinvention, they die mechanism includes a pair of supporting members 88and 85, to which are attached by a lost motion connection a plurality ofdie members and to which are fixed specially formed plungers.

In this form of the invention, the die members include a pair of annularouter die members 81 and 88 connected, respectively, to the supportingmembers 89 and 85 by means of a plurality of member 85, comprising astud studs 89 and 90. The studs 89 are threaded into suitable openingsin the supporting member 84 and are locked into position by lock nuts 9.

The shanks of these studs extend through suitable openings 92 in theupper annular die member 81, and are provided with enlarged heads 93adapted to slide in the lower counterbored portions of the openings 92.The studs 90, which. connect the lower die member 88 to the lowersupporting member 85, are threaded into suitable openings in thesupporting member and are locked into position by lock nuts 84. Theshanks of the studs 90 project through openings in the annular diemember 88 and enlarged heads 95- on the studs slide in the uppercounterbored ends of the openings 95. It will be noted that thecounterbored portions of the openings 92 and 95 are in alignment, sothat when the die members 81 and 88 are closed upon each other, in themanner shown in Figure 6, the head 93 of stud 89 may project downwardlyinto the counterbore of opening 95. The annular die members 81 and 88,which extend entirely around the mechanism, are normally held in spacedrelation to the supporting members 84 and 85 by means of a plurality ofsprings 98 and 99.

Secured to the lower supporting member 85 by a similar lost motionconnection are four generally sector-shaped die members I02, each havingan arcuate surface I03 concentric with the inner surface of the annulardie member 88 and spaced from it and a pair of substantially radial Thewheel is supported in position in the diemember by a cylindricalsupporting element IIO having an integral locating pin III, which isadaptedv to fit the interior opening of the hub 80. The cylindricalsupporting member' IIO has a lost motion connection with the lowersupporting II2, which is screwed into thebottom of the supporting memberH0 and extends through a suitable bore H3 in the supporting member 85.An enlarged head cesses during the performing operation. It will benoted that the outer surface of the wheel supporting member H0 is spacedfrom the inner arcuate surface I08 of the sector-shaped die members I02.

It will be observed that the spaces between the members 88, I02 and II0, as viewed in Figure 5, define inner and outer concentric circlescon-r nected by four radial hubs. Consequently, there is provided on thelower die member a plunger, indicated generally at I I8, which is of ashape to fill those spaces. The plunger II8 thus includes an annularportion II9, which fills the space be- 7 tween the outer arcuatesurfaces I08 of the sectorshaped die members I82 and the inner arcuatesurfaces I20 of the outer annular die 88. The plunger M8 also includesfour radially extending portions iii, which fill the spaces between theradial side walls I 3 of the sector-shaped die members I82; and theplunger I58 further includes an inner annular portion I22, which fillsthe spaces between the wheel" supporting member I I0 and the innerarcuam surfaces I08 of the die members I02. The entire plunger H8 isfixedly secured to the lower supporting member 85 by a plurality of capscrews I28.

The inner die mechanism mounted upon the upper supporting member 88 issimilar to that just described with reference to the lower supportingmember 85, and includes four inner die members I having the samesector-shape as the die members I02 and connected to the uppersupporting member 84 by a lost motion connection including studs l3l andsprings I32. In addition, there is provided a central cylindrical dieelement nae having an am'al bore 335 to receive the upper end of the pinIII. The lower surface of the die member I36 rests upon the upper end ofthe hub sleeve 88 when the die members are closed in they manner shownin Figure 6.

The die element are likewise has a lost motion connection with the hubsupporting member 84 comprising a stud I36 and a spring I37,

The die members 8'5, I38 and I34 are similar in shape and arrangement tothe corresponding die members 88, I02 and H8 mounted on the lowersupporting member 85, except that the inner arcuate surface I33 of thesector-shaped 1 die members I30 is of larger radius than thecorresponding surfaces I08 on the sector-shaped die members I82 in orderto provide room for the reinforcing ring 83 of the steering wheel frame.It, will be observed that, as shown in Figure 6, the reinforcing ring 83rests upon the upper inwardly projecting surfaces of thesector-shapeddie memhatch lines.

closed in the position shown in Figures 5 and 6 and the plastic materialis injected through an opening I82, shown at the left-hand side ofFigure 6. From this point the material fills all of the die spaces, as.indicated by the broken cross- If necessary, additional openings may beprovided to facilitate filling the die spaces.

After the die is filled with plastic material, the supporting elements84 and B5 are moved toward each other until the plastic material isfully compressed, such closing movement being accompanied by acompression of the springs 98, 88, Ml, M5, I32 and E31. This finalclosing movement compressesthe plastic material about the rim, spokesand hub sleeve of the steering wheel frame or core. In addition; it willbe observed that it compresses a body of plastic partially around thereinforcing ring 83. The only point at which the reinforcing ring 83will not be surrounded by plastic is at that portion at which itcontacts the sector-shaped die members I02. There will, however, besuflicient plastic in the general vicinity of the supporting ring I03 tocompletely envelop the ring in the final molding operation.

It will be noted that the mating edges of the various pairs of diemembers 87-88 and I02--I 88 are slightly beveled, as indicated at I46,in order bers I02 when the parts are in the position shown.

This facilitates location of the rim 82 but, if desired, a clearance maybe provided between the reinforcing ring 83 and the die members I02.

The upper supporting member 84 also includes a plunger which is of thesame shape and arrangement as the plunger H8 and which includes an outerannularportion I38, four radially extending portions I39, and an innerannular portion I48, the latter being of greater width than thecorresponding inner annular portion I22 on the lower plunger; II8 due tothe greater space between the surface I33 and the periphery of the diemember I34.

The operation of the modified form of die mechanism will be obvious fromthe description of the operation of the form of die mechanism shown inFigures 1 through 4. The supporting member 84 and .85 are firstseparated from the position shown in Figure 6 in order to provide roombetween the die members or insertion of the steering wheel frame orcore. Duringsuch operation, the heads on the various studs cause aseparation of the work holding die element IIO from the die element I34,a separation of the die), elements I02 from the die elements I30, and aseparation of the annular dieelements 88 from the die elements 81, inspite of the action of the such die v elements toto facilitateseparation of the die members and removal of the preformed material.

During the preforming operation the plungers do not advance intooverlapping relation with respect to the beveled surfaces, the partsbeing so designed that the closing movement of the press is blocked whenthe plungers reach the edge of the beveled surface.

It will be noted that there is less compression of the plastic materialprovided for in the die mechanism of Figures 5 to 7, inclusive, than inthe die mechanism illustrated in Figures 1 through 4. The difference isaccounted for by the fact that the modified form of die mechanism wasdesigned for use with a plastic which did not have as high a ratio ofcompression during the preforming operation as the particular plasticintended for use in the die mechanism of Figures -1 through 4.

It will'be understood that if either form of apparatus disclosed hereinis employed in premolding a plastic material, such as rubber, which issupplied in roughly shaped slabs or pieces rather than in particulatedform, the plastic material will be inserted in the die recesses at thesame time that the core piece is inserted, i. e. while the die membersare fully separated. Use of the apparatus and employment of the method,described herein makes it possible to quickly and easily preformexactly the right amount of plastic material entirely about thecore-piece and to equally distribute that'material so that a minimumamount of flow of material will occur during the final moldingoperation. In consequence, the final molded product is stronger and moreuniform in its properties and all waste is eliminated,

It is apparent that various modifications may be made in the apparatusand method described above without departing from the spirit of theinvention or thescope of the appended claims.

What is claimed is:

1. A preforming die for compressing plastic material around a coremember including a pair of supportingmembers movable toward and awayfrom each other, means adapted to form a closed chamber for reception ofthe core and material,

said means including a pair of mating upper and lower side wall formingmembers located between the supporting members and a pair of plungersfixedrespectively tosaidsupporting member and forming the top and bottomwalls of the chamber, resilient means for forcing each mating memberaway from its adjacent supporting member and toward the othermatingmember, a lost motion connection between each mating member andits adjacent supporting member to permit limited movement of thematingmember toward and away from the supporting member whereby on fullseparation of the supporting members the mating members will beseparated from each other to permit insertion of a core member and onpartial movement of said supporting members toward each other saidmating members will contact each other and close the chamber without anymovement of either mating member with respect to the supporting memberto' which it is connected, means on one of said mating members .tosupport the core member in spaced relation to the. walls of thechamber,-said chamber having an aperture to permit injection of saidmaterial when the chamber is closed, said lost motion connectionpermitting said supporting members and plungers to move toward eachother and compress the material around the core after the mating memberscontact and close the chamber.

2. A pretorming die for compressing plastic 1 "of mating members adaptedto define the outer side wall of said annular chamber, and a pair ofplungers movable toward each other with said supporting members anddefining the top and bottom walls of said chamber, a lost motionconnection between each of said supportin members and the adjacent oneof each of said pairs of mating members to cause separation of saidpairs when said supporting members are fully separated, resilient meansto cause said mating membars to contact each other and close saidchamber when the supporting members are moved partially toward eachother, said lost motion connection permitting said supporting membersand plungers to move toward each other and compress the material aroundthe core after the mating members contact and close the chamber.

3. A preforming die for compressing particu lated material around anannular coremember including a pair of supporting members movable towardand away from each other, means adapted to form a closed annular chamberlocated be- 1 tween said supporting members for reception of said core,said means including a pair of mating upper and lowermembers adapted todefine the inner side wall of said annular chamber, a pair of saidchamber, a lost motion connection between each of said supportingmembers and the adjacent one of each of said pairs of mating members tocause separation of said pairs when said supporting members are fullyseparated, resillent means to cause-said mating members to contact eachother and close said chamber when the supporting members are movedpartially towardeach other, means on one of said mating members tosupport the core member in spaced relation to the walls of the chamber,said chamber having an aperture to permit injection of said materialwhenthe chamber is closed, said lost motion connection permitting saidsupporting members and plungers to move toward each other and compressthe material around the core after the mating members contact and closethe chamber.

4. A preforming die for compressing particulated material around the Fimof a spoked wheel including a pair of supporting members movable towardand away from each other, means adapted to form a closed annular chamberlocated between said supporting members for reception of said wheel rim,said means including a pair of mating upper and lower members adapted todefine the inner sidewall of said annular chamber, a pair of matingmembers adapted to define the outer side wall of said annular chamber,and a pair of plungers fixed respectively to said supporting members anddefining the top and bottom walls of said chamber, a lost motionconnection between each of said supporting members and the adjacent oneof each of said pairs of mating members to cause separation ofsaid pairswhensaid supporting members are fully separated, resilient means tocause said mating members to contact each other and close said chamberwhen the supporting members are movedpartially toward each other, meanson one of said pair of innerside wall mating members to engage the wheeland support the same with the rim in spaced relation I v the materialaround the core after the mating to the walls of the chamber, saidchamber having an aperture to permit injection of said'material when thechamber is closed, said lost motion connection permitting saidsupporting members and plungers to move toward each other and compressmembers contact and close the, chamber.

5. A preformiiig die for compressing plastic materialabout the rim,spokes and hub of a spoked wheel including a pair of supporting membersmovable toward and away from each other, means suspended between andhaving a lost motion connection with said supporting members and adaptedto form a closed chamber of a shape corresponding to the shape or thewheel, said means including co-operating members defining the side wallsof said chamber, said side walls lying parallel to the path of relativemovement a of said supporting members and along both the inner and outersides of the rim, both sides of each spoke and the outside of the hub ofthe wheel, a pair of plungers carried respectively by said supportingmembers and projecting toward each other and into the space between saidsidewalls, said plungers being of a size and shape to fill the spacebetween said side walls and being adapted when the supporting membersmove toward each other to move toward the wheel and each other andcompress plastic material toward and around the rim, spokes and hub andmeans for supporting the wheel in said chamber in spaced relation tosaid walls, said last mentioned means including springs acting againstthe supporting members for holding the wheel in spaced relation tobothmlungers as the plungers move toward each other.

' MAGNUS M. BI JRGESS.

